1. Field of the Invention
The invention relates to wireless monitoring, and, more particularly, to wireless monitoring of solar trackers.
2. Description of the Related Art
A typical commercial solar plant consists of several thousands of solar trackers. For optimal performance, trackers may point to the sun's position so as to capture a maximum amount of solar energy. Because the sun's position in the sky is constantly changing, pointing the trackers at the sun may require continuous tracking. A control station may govern the tracking by sending commands to each individual tracker over a wired network. The control station may also perform continuous condition monitoring of the trackers by receiving status messages from the trackers. Connecting thousands of trackers to the central control station via wires is a cumbersome process requiring a lot of time and incurring huge cost.
Commercial solar plants may include thousands of tracking collectors (i.e., trackers) to capture the solar energy. These tracking collectors can convert solar energy to electricity via either of two methods. In the first such method, sometimes referred to as “Concentrated Solar Power” (CSP), the trackers include mirrors which focus the sun's rays on a heat collector. The heat energy is then later converted to electricity. In the second method, sometimes referred to as “Concentrated Photovoltaic” (CPV), the trackers include photovoltaic modules which convert solar energy to electricity directly.
For optimal performance, the trackers may continuously point in the direction of the sun. Also, during non-operation, at night, or during inclement weather conditions (e.g., rain, snow, etc.), the trackers may return to the safe position in which they are protected. The position of each of these trackers may be controlled from and by a central data control station (DCS) that transmits commands and receives status messages from the trackers using wired communication.
FIG. 1 illustrates a known wired data communication hierarchy 10 for parabolic trough CSP systems. Hierarchy 10 may include fiber-optic point-to-point links 12 between the DCS and the data concentrators. Hierarchy 10 may also include wired RS-485 or fiber-optic point-to-point links 14 between the data concentrators and the data collectors. Hierarchy 10 may further include a tracking system 16 (e.g., “tracker”) having data collectors and hydraulic and power units for a parabolic trough.
Tracking requirements and solutions may be the same for CSPs and CPVs from a communications point of view. A typical solar plant includes thousands of trackers, so the plant may cover several square kilometers of area. Thus, connecting each of these trackers with a DCS may require several kilometers of wire as well as a huge cost and installation effort.
What is neither disclosed nor suggested by the prior art is a method of controlling a group of solar trackers that overcomes the above-described problems.